1. Field of the Invention
The present invention relates generally to regulator valves useful in creating and maintaining a selected pressure in a gas pipe or conduit. More specifically, the present invention relates to a regulator capable of creating and maintaining two pressure reductions in series with each other within a single regulator body.
2. Description of Related Art
Regulator valves for controlling the pressure of a gas pipe or conduit are well known in the art. There are many ways to regulate the flow rate to equal demand and thus maintain a constant pressure of the gas pipe or conduit independent of inlet pressure and/or load fluctuations. In some applications, several gas-flow regulators are connected in series such that if one regulator fails to control outlet pressure the second regulator takes over control. Most regulator valves include a mechanism, such as a cage or throttle plate, for restricting the flow of the gas stream and creating the pressure drop. These cages and throttle plates usually include a variety of holes or slots through which a selected portion of the gas stream is allowed to flow by altering the position of the diaphragm. Many of these regulator valves include additional control valves for actuating the main gas-flow regulator valve.
As the technology advanced, gas-flow regulator valves began to include control valves having one or more additional pilot amplifier valves with closed-loop feedback capabilities. These pilot valves generally contained a sensing pressure chamber and an actuator that positions the pilot valve. The pressure inputs to these pilot valves could be connected to a loading chamber that is in fluid communication with the throttling diaphragm of the main regulator such that inlet pressure can be applied to the diaphragm to position the diaphragm correctly. In addition, it was not uncommon to connect more than one pilot valve to a single flow regulator. The control pressures within these pilot valves could be derived from the pressure of the gas stream upstream of the main regulator, (back pressure regulator), or the pressure of the gas stream downstream of a throttling regulator.
Despite these advances in the art, there continues to be a need for improved regulator construction and control system in order to increase efficiency, provide improved reliability, and decrease operational noise, while decreasing the cost of regulator maintenance.